Your Basement is made of Porous Concrete

Concrete is porous. Most homes have a basement that is made of concrete. There are mainly two types of concrete foundations on homes here in New Jersey.

The first is a poured solid concrete 8" thick concrete wall. There are also poured walls that are 10" or 12". An excavation is done to an average of eight feet. This depth is well below the frost line of 18" to 20". The depth below the frost line is where water NEVER freezes. Next a concrete footing is poured, typically 16" wide for an 8" wall. Next, forms of either metal or wood are constructed on top of the footings. The forms are usually held together with metal tie rods. The concrete is poured in between the forms and allowed time to set. After the concrete sets, the tie rods are cut, the forms are removed and the 8" thick poured concrete walls remain. A 4" slab floor is then poured. The outer edge of the floor rests upon the footing.

The second type is a masonry wall made with concrete block. Concrete block foundations are made from pre-formed hollow blocks. The blocks are also called cinder blocks, or more technically, CMUs (Concrete Masonry Units). Construction begins the same way, an excavation is made and a 16" wide footing is installed below the frost line. The most common concrete blocks are 8" deep x 8" high x 16" wide. These 8" blocks are centered on the 16" wide footings and built up in courses. A typical configuration is 11 courses of 8" block for a wall height of 7'3". A 4" slab floor is then poured. The outer edge of the floor rests upon the footing.

During construction a type of waterproofing is usually applied to the foundation before the backfill is done. A tar like substance is applied to the exterior of the concrete walls, both poured and block alike. Tar is a very good waterproofing substance and has been used forever. Noah used tar on the ark and it has been used ever since. While Noah needed protection for forty days and forty nights, the tar applied to most homes is good for 30-40 years or so. The tar coating is similar in substance and life to roofing shingles. They don’t last forever and neither does the tar on the foundation.

Once the tar is gone the foundation is no longer sealed. The porous concrete is laid bare. Water creeping through underground soil crevices creates hydrostatic pressure up from beneath the floors and against the sides of your home. Hydrostatic pressure is when a body of water surrounds something that does not float. When this water pressure forms around the foundation the un-sealed concrete starts to absorb the water. This is called capillary action. Let's do a visual; we have a sponge cube that is 12"x12"x12". We take the cube and prop it up on 1" blocks and place it under the kitchen faucet. We then let one drop of water drip on the center of the sponge every second. The sponge gets saturated right down the center until the center of the sponge is wet all the way down to the bottom. From this point forward for every drop of water that hits the top of the sponge, a corresponding drop of water will come out of the bottom of the bottom of the sponge. The water no longer has to pause in its journey to be absorbed by the concrete because absorption has already occurred. Now the water just passes right through the saturated concrete. This is called capillary suction. The water comes right into the concrete. The concrete is porous, it absorbs and retains water.

If this water damage is left untreated, repairs for this type of damage can be quite overwhelming. The earlier these abnormalities in your home are addressed, the better off you will be. The best way to prevent negative consequences from occurring is to ensure that you are aware of the measures you can take to prevent them from happening in your home. For your peace of mind, call a professional Basement Waterproofing Contractor to get an inspection